The car is not on some scientific voyage. This was a test launch, so SpaceX needed a dummy payload -- and Musk previously said he wanted it to be the "[s]illiest thing we can imagine." So he picked his own luxurious Tesla roadster.

"I love the thought of a car drifting apparently endlessly through space and perhaps being discovered by an alien race millions of years in the future," he said in December.

Shortly after the launch, SpaceX posted a live feed of Starman's journey. The images looked as if they were plucked from science fiction.

"I think it looks so ridiculous and impossible, and you can tell it's real because it looks so fake, honestly," Musk said at a press conference Tuesday. "We have way better CGI (computer-generated imagery)" than that.

The livestream, which was later viewed by millions of people, cut out after about four and a half hours when cameras' batteries died. Onlookers here on Earthmoved on with their lives.

But Starman and the Tesla are still out there, and late Tuesday the second-stage engine gave them a final boost, putting them on a path toward orbit around the sun.

More than likely, they will remain drifting through the vacuum of space for generations to come. Astronomers have been hard at work pinning down exactly what path they will take.

At first, Musk suggested on Twitter that the Tesla overshot its intended orbit and would fly out past Mars and into the asteroid belt.

But now experts say that probably won't happen.

NASA's Jet Propulsion Laboratory got its hands on data from SpaceX on Wednesday, and it suggests the roadster will stay closer to the sun. The farthest it will go is about 250 million kilometers from the sun, or about as far as Mars.

Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, says he also got a first-hand glimpse at the data and his analysis lines up with NASA's.

It'll reach its farthest point from the sun in November, and in September 2019, it will complete its first full loop around the sun. It'll continue to complete one full orbit about every 19 months.

That's based on current projections, but things can always change.

"The problem now is that it's kind of difficult to predict how the orbit will evolve," said Marco Langbroek, a space expert who tracks asteroids.

He said forces like solar radiation can slowly bump the roadster toward a different course, or leftover gas in the second-stage rocket could give it another heave.

By next week, astronomers say, the car will already be too far away from Earth to track with telescopes. So they're clamoring to get some good shots of the roadster now.

Because of how the car's projected orbit aligns with Earth's orbit, astronomers on the ground probably won't be able to spot the roadster again until late in the 21st century. Based on calculations he made Thursday, Langbroek predicted that could happen in 2073. But in an email on Friday, he said it still seemed the car's path was "too ill defined to make reliable forecasts."

At that point, "it's certainly possible that it will be mistaken for an asteroid," he said. Astronomers will eventually be able to figure out its a man made object, however, by observing its "orbit and behavior and brightness."

And NASA says the roadster has been added to is "artificial object catalog" in an attempt to prevent this kind of confusion, according to Dwayne Brown, a senior communications official at NASA.

McDowell, half jokingly, predicts astronomers won't have to worry about it at all.

By the late century, he said, he imagines humans will have already colonized other planets in the solar system -- and Musk's "descendants will be able to drag [the roadster] back to a museum."